Bottom discharge means for silo

ABSTRACT

Bottom discharge means for silo having a cylindrical shell provided with a top and bottom, the bottom having a discharge opening adjacent the center, an auger having a coarse pitch and flexible dislodging members which ultimately extend radially are connected to a shaft extending upward through the bottom of the silo shell, and a housing depending from said bottom and provided with a discharge guide sloping downwardly and outwardly to a discharge port having a closure provided with dislodging means when initially moved to open position, one embodiment of the invention having an auger-type removal means communicating with the discharge port and another embodiment having a blower connected by a chute to the discharge port and the closure member serving additionally as a means to regulate the amount of air delivered to the entrance of the fan. Loading and vent means extending to the top of the silo also are provided to prevent the necessity of climbing to the top of the silo at any time during unloading or loading thereof. Additionally, auxiliary unloading means are detachably connectable to the shaft and auger for purposes of removing the remaining, conical-shaped residue of compacted material in the bottom of the silo when the same otherwise is empty.

United States Patent Inventors John I-I. I-Ierr Lebanon; Aaron Z. Stauffer, Ephrata, Pa.

Appl. No. 793,489

Filed Jan. 23, 1969 Patented Mar. 2, 1971 Assignee Flying Dutchman Mfg. & Sales Co., Inc.

Lebanon, Pa.

Continuation-impart of application Ser. No. 634,534, Apr. 28, 1967, now Patent No. 3,424,350.

BOTTOM DISCHARGE MEANS FOR SILO 22 Claims, 18 Drawing Figs.

2,795,080l 6/l957 Williams Primary Examiner-Stanley H. Tollberg Attorney-C. Hercus Just ABSTRACT: Bottom discharge mea-ns for silo having a cylindrical shell provided with a top and bottom, the bottom having a discharge opening adjacent the center, an auger having a coarse pitch and flexible dislodging members which ultimately extend radially are connected to a shaft extending upward through the bottom of the silo shell, .and a housing depending from said bottom and provided with a discharge guide sloping downwardly and outwardly to a discharge port having a closure provided with dislodging means, when initially moved to open position, one embodiment of the invention having an auger-type removal means communicating with the discharge port and another embodiment having a blower connected by a chute to the discharge port and the closure member serving additionally as a means to regulate the amount of air delivered to the entrance of the fan. Loading and vent means extending to the top .of the silo also are provided to prevent the necessity of climbing to the top of the silo at any time during unloading or loading thereof. Additionally, auxiliary unloading means are detachably connectable to the shaft and auger for pur- 'poses of removing the remaining, conical-shaped residue of compacted material in the bottom of the silo when the same otherwise is empty.

met

PATENTEUMAR am @Lsg/.079

SHEET 1 DF 4 INVENTORS JOHN H. IHERR Y AARON' Z. STAUFFER ATTORNEY `PATENTEU HAR 2 |911 4 GLS-61078 suesaufa,

`.z T 34 s? 22) fila u, r fc4/firing nl 7/ 'c' ATTORNEY PATENTEUMAR 2mn 3567.078

INVENTORS JOHN H. HERR *IFI By AARON Z. STAUFFER BOTTOM DISCHARGE MEANS rok sito CROSsREFERENcI-z To RELATED APPLICATION 5 The present Invention comprises, In varlous respects, Im-

provements over the structurel illustrated and claimed in copending application, Ser. No. 634,534, filed Apr. 28, 1967, now U.S. Pat. No. 3,424,350 and is a continuation-in-part thereof.

BACKGROUND OF THE INVENTION materials, and various other types-of material which have a.

tendency to compress and compact during storage. The greatest density obviously occurs at the bottom which, therefore, is the most logical location to provide unloading means for purposes of discharging the material, as desired, from the silo.

Many attempts have previously been made to provide bottom discharge mechanism for silos to be used in connection with different materials. Certain of these have included augers of relatively coarse pitch, flexible chains supported by vertical shafts which flail around as the shaft rotates and gradually dislodges the material. Apparatus of Vthis type is illustrated in the following U.S. Pat. Nos.: 2,228,421, to Taylor, issued Jan. I4, 1941; 2,576,620, to Martin, issued Nov. 27, 1951; and 3,138,300, to Rintala, issued Jun. 23, 1964.

Other types of bottom unloader means have included radially extending arms provided with toothed gears or the like on the outer ends thereof engageable with circular racks extending around the lower portion of the silo and such arms being intended to be driven around the lower portion of the interior of the silo for purposes of dislodging compacted material. Examples of this type of unloading means are illustrated in the following U.S. Pat. Nos: 2,551,217, to Martin, issued May 1, 1951; and 3,067,914, to Ellaby, issued Dec. ll, 1962.

In general, bottom unloading devices of the type referred to have not been appreciably satisfactory because difficulties are usually experienced at the time initial operation of the unloading mechanism is instituted. Initiating the movement of dislodging means at the bottom of a silo within highly compacted and dense material, particularly of a moist nature, is extremely difficult, requires extensive power and frequently results in damage to the mechanism, even where substantial care is exercised in operating the same.

One other difficulty existing commonly in regard to sealed types of silos and particularly `silos of appreciable height is the fact that, during the loading thereof, it normally is necessary to climb to the top and open vent means to permit the escape of internal air and gases when loading of the silo is taking place. At the completion of such operation, it also is necessary to climb to the top again and close the vent against the ingress of the ambient atmosphere.

Still another difficulty normally experienced in unloading silos of the type referred to comprises the fact that conventional unloading mechanism usually forms a compacted mass on the bottom or floor of the silo which has a conical upper surface extending upward and outward from the central axis and facilities the discharge of loosened material as the unloading mechanism operates while the material in the upper portion of the silo gradually lowers by gravity. When the upper material has been exhausted however, problems exist with regard to dislodging the remaining compact residue in the bottom of the silo. Not infrequently, it is necessary for a person to climb into the bottom portion of the silo and manually dislodge the material by suitable rudimentary tools.

SUMMARY or THE INVENTION It is the principal purpose of the present invention to provide bottom unloading means for a silo 'which obviate difficulties of existing mechanisms referred to above. To accomplish this, the present invention includes a vertical shaft which extends through the bottom of a silo toward the top for a predetermined distance and supports an auger of coarse pitch together with flexible dislodging means, such as a series of chains or suitable arms having digging members on the outer ends thereof which initially are draped along the shaft and auger when the silo is being loaded. A discharge opening is provided in the bottom of the silo adjacent said shaft. The flexible members have a length less than the radius of the silo and the lower members are shorter than theupper so that a compacted residue of material is formed adjacent the bottom which has a generally conical or sem'ispherical upper surface configuration. v

Another object of the invention is to provide a housing immediately below the discharge opening in the bottom of the silo, the same having outwardlyl and downwardly sloping discharge guide means for the material leading to a discharge port normally sealed by a closure which preferably is hingedly supported adjacent the top thereof and having a dislodging member, somewhat in the nature of a rake, operable to remove the compacted material immediately adjacent the closure when the closure is opened a'nd thereby facilitate discharge of material through the discharge port into suitable means to receive the same without ingress of atmospheric air.

A further object of the invention is to provide, selectively, either a relatively simple type of material removing means adjacent said discharge port and having, for example, an auger operable to transport the material upwardly, due to the fact that such removal mechanism generally will be in a cavity or pit beneath the bottom of the silo andusually below ground level, or an additional, higher capacity type of removal means comprising a blower connected to the discharge port of the aforementioned guide means by a chute having at least a partially opened top, whereby the i closure member for the discharge port serves the dual function of closing said discharge port and also being mov'able .to adjusted distances between said discharge port and the top of said chute which is arranged to be closed by said closure member when in the extreme outermost position away from said discharge port, thereby controlling the amount of ambient air which is capable of entering the inlet of the fan together with material being blown by the fan through a suitable discharge conduit to a desired location, in substantial quantities, without ingress of ambient atmosphere into the silo interior when discharging material therefrom.

Still another object of the invention is to provide silo filling means of a tubular nature extending up the exterior of the silo shell and having a discharge end in the top of the silo, preferably centrally thereof, in combination with a tubular vent conductor, which'also preferably extends exteriorly upward relative to the silo shell and communicates at its upper end with a vent opening in the top of the silo, the lower end of the vent conductor having air passage regulating means by which the conductor also may be sealed against the ingress of exterior atmosphere at the completion of a Afilling operation.

A still further object of the invention is to provide auxiliary bottom unloading means capable of removing the compacted residue of material adjacent the bottom of a silo after all the material previously above the same has been removed, such auxiliary removal means being readily installed for use and being capable of power operation to remove substantially all of the material from the silo to 4and through the discharge opening in the bottom thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation, partly in section, showing one embodiment of bottom unloading means, the silo shell being brokenmidway to foreshorten the same and thereby accommodate it to the sheet.

FIG. 2 is a fragmentary side elevation of another embodi-4 ment of bottom unloading mechanism from that illustrated in FIG. l, as seen on the linef22 of FIG. 3.

FIG. 3 is an end view of the embodiment of unloading mechanism shown in FIG. 2, as seen on the line 3-3 of FIG. 6.

FIG. 4 is a fragmentary, enlarged view of a portion of the mechanism shown in FIG. 2 to illustrate details of the operation thereof.

FIG. 5 is a fragmentary exterior front elevation of the portion of the mechanism shown in FIG. 4.

FIG. 6 is a top plan view of the embodiment of mechanism shown in FIGS. 2-and 3 and further showing the power mechanism for the shaft and auger illustrated in side elevation in FIG. l.

FIG. 7 is a fragmentary top plan view of a portion of the mechanism shown in FIG. l as seen on Vthe line 7-7 thereof.

FIG. 8 is an enlarged top plan view of a portion of the mechanism shown on the line 7-7 of FIG. 1 and illustrating further details thereof.

FIG. 9 is a side elevation of the mechanism shown in FIG. 8 as seen on the line 9-9 thereof.

FIG. 10 is a fragmentary side elevation of part of the mechanism shown in FIG. 1 as see-n on the line 10-10 thereof and illustrated on a larger scale than in FIG. I.

FIG. 11 is a top plan view of the silo shell shown in FIG. 1 and illustrated on a smaller scale than in said FIG.

FIGS. 12 and 13 respectively are small scaleillustrations of arrangements of multiple bottom unloading units primarily for use in silos of abnormal diameters from those commonly employed.

FIG. I4 is a fragmentary vertical sectional view of part of the lower portion ofthe silo shell and bottom shown in FIG. l and illustrating auxiliary removal or unloading means.

FIG. l5 is a fragmentary plan view of the mechanism shown in FIG. 14 as seen on the line 15-.15 thereof.

FIG. I6 is a fragmentary, enlarged horizontal sectional view of a part of the mechanism shown in FIG. 1.4 to illustrate bracing structure therein.

FIG. 17 is a fragmentary transverse sectional view of details of the mechanism shown in FIG. 16 as seen on the line 17-17 thereof.

FIG. 18 is an enlarged vertical sectional view of air flow control mechanism shown in FIG. l on the line 18.18 thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In referring to the present invention comprising a bottom unloader for a silo, it is to be understood that the silo is the type which may be used for storing material of many different kinds and types. One very common use for such type of silo is in regard to storing agricultural products such as silage which contains a substantial amount of moisture an preferably must be preserved in suitable condition for healthful consumption by farm animals of different types and particularly dairy herds and steers.

When used for such purposes, it is preferred that the silo shell be of such type as to resist reaction from the contents of the silage. Several different appropriate and acceptable types of silos for such use comprise those which are made from cement and others which are formed from sheet metall suitably coated by vitreous material which is fused to the surface thereof or by the use of impervious liners. However, it is to be understood that silos for many other uses may be used in conjunction with the present invention, such as those used to store dryer types of material such as wood chips, other forms of dry agricultural products, granular materials, and numerous other types of material which, for general purposes of describing the application of the present invention, are commonly referred to as pulverant material.

Silos of the type to which the present invention pertain may range in diameters of l0 or l2 feet, up to 30 or 40 feet depending upon the type of material to be stored therein. The heights may range variously between 25 or 30 feet to as much as 75 or 80 feet, or even higher. The structure of the silo shell must be suitable to withstanding the bursting pressures imposed bythe material stored therein, particularly when the silo is substantially filled with such material.

From these ranges of diameters and heights however, it readily can be visualized that the weight of the material per se within such a silo, particularly when nearly filled, is such that the material adjacent the bottom of the silo-is placed under very appreciable pressure which results in highly compacting and condensing the material. This adds greatly to the problem of unloading such a silo by discharging the material particularly from the bottom thereof, as is the mostl common and desired practice. Accordingly, the bottom unloading mechanism and especially the various embodiments thereof which are described hereinafter and are illustrated on the attached drawings comprising a part of this application are particularly suited toprovide efficient unloading of the silo from the bottom, through an appropriate discharge opening therein, with a minimum consumption of power and with minimum requirements of upkeep, repair, and servicing.

Referring to FIG. l, it will be seen that an exemplary silo shell 10 is shown which preferably is cylindrical in plan view. As illustrated, it is formed from concrete and may be provided with a suitable interior lining or coating, if desired, to render the same more resistant to reaction by the material stored therein, or otherwise to render the same impervious to the passage of air. The upper end ofthe shell 10 is closed by a suitable top or cover 12 which has an inlet or filling opening 14 disposed preferably centrally of said top and a vent opening 16 which preferably is adjacent one edge of the top and at a lower level than the inlet opening 14. The shell 10 is supported upon a conventional foundation 18 which, for example,

l usually extends into the adjacent ground and forms an interior pit 20 for purposes to be described.

The lower portion of the silo shell l0 is also provided with an appropriate bottom 22 which may be formed suitably from concrete, appropriately reinforced, and otherwise supported by a series of transversely extending beams 24 of steel or otherwise. Depending below and supported by the beams 24 is a discharge housing 26 which may be formed from suitable sheet metal or the like. Preferably, the housing 26 is coaxial with the silo shell I0 and extends into the pit 20 which is of sutabletsize to accommodate the same.

Disposed within the housing 26 is a discharge guide 28 which also may be formed from sheet metal or the like and extends downwardly from its upper edge at one side of housing 20 substantially to the bottom of the opposite side of said housing and terminates in a discharge opening 30. The top of housing 26 is provided with an inlet opening 32 which, as best shown in FIG. 7 in plan view, is semicircular. Extending between a pair of the beams 24 are short struts or beams 34, one of which supports a bearing block 36 comprising one bearing for a vertical shaft 38. A lower bearing block 40 is supported by another transverse strut 42 which is,v secured at its opposite ends to opposite sidewalls of the discharge housing 26.

Referring to FIGS. 1 and 6, it will be seen that an appropriate bracket 44 is affixed to one sidewall of discharge housing 26 for purposes of supporting suitable power means comprising preferably an electric motor 4,6. A small sheave 48, which may be of the dual type if desired, as shown in exemplary manner in FIG. l, is fixed to the lower end of the drive shaft of motor 46. A pair of suitable brackets 50 support bearing blocks 52 between which a power transfer shaft 5 4 extends. A larger sheave 56 is fixed to the lower end of shaft 54 and a smaller sheave 58 is fixed to the lower end of shaft 38. Appropriate endless flexible members such as belts 62 and 64 extend respectively around smaller sheave 48 and larger sheave 56, and around smaller sheave 58 and larger sheave 60, thereby affording a very substantial speed reducing and power multiplying arrangement, whereby a relatively small horsepower motor 46` may be used to drive the shaft 38 and mechanism connected thereto which will be described hereinafter within stored and compacted material particularly in the lower portion of the silo shell 1 0.

Referring again to FIG. 1, it will be seen that a spiral auger 62, preferably having a hollow axis, is received at its lower end upon the upper end of drive shaft 38. Said shaft preferably extends axially upwardly into the hollow interior of the bore of auger 62 a substantial distance and is affixed for rotation thereto by a plurality of bolts 64, one o f which serves an additional function to be described in detail hereinafter. The auger 62 preferably is of substantial diameter and coarse pitch. One practical diameter for said auger, which has been found to be highly suitable in a silo l2 or l5 feetin diameter, is 9 inches. The pitch of the convolutions of the spiral flight also is of similar dimension. It is to be understood however that these dimensions are merely illustrative and not restrictive.

The lower end of the auger 62 is slightly spaced from the upper surface of the bottom 22 of the silo for purposes of accommodating a radially extending wiping blade-66, details of which are best shown in FIGS. 8 and 9, respectively comprising a plan view and a side elevation thereof. A simple strap 68, of suitable shape, issecured to the blade 66 by a pair of bolts 70 of any other suitable means. Further to lock the blade 66 nonrotatably to the shaft, a setscrew 72 shown in said FIGS.

` preferably is arranged to extend into'a suitable recess extending radially into the shaft 38. The function of the blades 66 is to wipe the upper surface of the bottom 22 of the silo substantially clean relative to the discharge opening 32 in the bottom 22 and also the upper portion of discharge housing 26 for purposes of facilitating material from the shell to pass into the discharge housing.

Auxiliary and flexible material-engaging and dislodging members also are supported by auger ,62. These are in the form of lengths of chain 74 and 76, having digging elements 78 on the outer ends thereof. The chains 74 are longer than chains 76 but none of the chains are greater than the radial dimension of the` interior of the silo `shell 10, whereby the digging element 78 on the outer ends thereof will never engage the interior surface of the shell 10. At the completion of a filling operation, the chains 74 and 76 will be draped downwardly and upon initiating rotation of shaft 38 and auger 62, the chains will become somewhat spiralled around the auger 62. However, as rotation of theauger continues, compacted material in the lower portion of the silo shell 10 will be loosened and discharged through the opening 32.

As material around the auger 62 passes from around the auger and is discharged through opening 32, the chains 74 and 76 gradually will be extended outward in a generally radial direction, by centrifugal force induced by elements 78, whereby the elements 78 will continue to dig into the cornpacted material and gradually loosen it and cause it to descend by gravity downwardly along the generally conical or semispherical upper surface 80 of compacted material 82 which, essentially, remains undisturbed until the silo has been emptied of all other material therein. Such shape is caused by the l difference in lengths of the chains 74 and 76 and facilitates the guiding of the loosened material toward and through the discharge opening 32.

As material around the auger 62 passes from around the auger and is discharged `through opening 32, the chains 74 and 76 gradually will be extended outward in a generally radial direction, by centrifugal force induced by elements 78, whereby the elements 78 will continue to dig into the cornpacted material and gradually loosen it and cause it to descend by gravity downwardly along the` generally conical or semispherical upper surface 80 of compacted material 82 which, essentially, remains undisturbed until the silo has been emptied of all other material therein. Such shape is caused by the difference in lengths of the chains 74 and 76 and facilitates the guiding of the loosened material toward and through the discharge opening 32.

When it is desired to remove or discharge a desired quantity of stored material from the bottom of the silo shell 10, the operation is as follows. Power is applied to motor 46 which operates the auger 62 preferably at a f'ixed speed. Due tothe coarse nature and substantial pitch of the spiral flight of the auger 62, it immediately commences to move the material immediately contacting the same downwardly through the discharge opening 32 into housing 26. Under most circumstances, a certain amount of material will fall through the opening 32 when the silo is being filled or following any previous discharge of material into housing 226. Such material will accumulate in the housing against the closure 84 which preferably is formed from sheet metal and is pivotally supported at its upper edge by a pivot rod 86, best shown in FIG. 6. Said closure extends between a pair of ears 88 which are fixed to opposite sidewalls of the discharge housing 26 and have axially aligned bearing openings therein to receive the rod 86.

As shown in FIG. l, an appropriate positioning arm 90 is keyed to closure 84, through rod 86 orotherwise, so as to control the movement and positioning of the closure relative to the discharge opening 30. If desired, the arm 90 may be flexible and `have a locking pin carried by a knob 92 operable to dispose the locking pin in any of a series` of arcuately arranged positioning holes 94E Preferably, the closure 84 also is provided with an appropriate gasket so as to render its closing engagement with the rim of the discharge port 30 substantially airtight. The closure 84 also supports from its inner surface a material removing element 96 which has a rakelike member on the outer end thereof engageable with compacted material adjacent discharge opening 30. Hence, when opening movement of closure 84 is initiated, the ralcelike element 96 will dislodge the lowerrnost material from adjacent the discharge opening and thus facilitate the passage of material through said opening which is being fed thereto by rotation of auger 62 and the ultimate functioning of `the dislodging members 74 and 76.

In the embodiment of the invention shown in FIG. 1, in which the removal of material primarily is intended to be controlled by manual operation of closure 84, said closure discharges into a short chute 98 which,.as best shown in FIG. 10, empties into the lower end of an upwardly extending conduit or conductor 100 within which a spiral auger 102 is rotated by means of another source of power such as motor 104 and any necessary gear reducer which drives universal joint 106. The conduit 100 usually will extend upwardly and outwardly relative to the discharge opening 30 due to the fact that the discharge housing 26 usually is in a pit below ground level.

In the embodiment of the invention shown in FIGS. 2 6, a blower discharge is provided for the rnaterial delivered to discharge opening 30. Referring particularly to FIGS. 2 and 4, it will be seen that the drive shaft 38 has been omitted for purposes of simplifying the illustration but it nevertheless will be understood that this embodiment of the invention includes such a drive shaft and the power means to rotate it, as well as the auger 62 on the upper end of the drive shaft 38. In these FIGS., it also will be seen that the closure 84 moves within a trough 108 which has opposite, preferably vertical and parallel sides 110, between which the closure'84 is pivotally movable between closing position with respect to the discharge opening 30 and the second position in which it closes the upper, normally open top of the trough 108.

As illustrated in broken lines in FIG. 4, the closure 84 is shown in the latter position in which it abuts the undersurfaces of a pair of laterally extending, relatively narrow inwardly directed parallel flanges 112, best shown in FIG. 5, and also as shown in FIG. 4. The normally lower edge of the closure 84 also will abut the undersurface of a top-plate 114 of the trough 108. When in such trough-closing position, the closure 84 seals the open top portion of the trough 108 for purposes now to be described. As in regard to the embodiment shown in FIGS. l and 10, the closure 84 illustrated in the embodiment of FIGS. 2-6 also is provided with position-maintaining means in the form of an exemplary arm 90, knob and locking pin 92, and arcuately disposed positioning holes 94. Other suitable means may be used, if desired.

Referring particularly to FIGS. 2, 3and 6, it will be seen that the discharge chute 108 empties into an inlet opening 116 in the sidewall of a blower housing 118 which is nearest the chute 108. The blower housing 118 also has a discharge opening 120 which communicates with an exit conductor or conduit 122 shown in FIG. 3. The blower housing 118 encloses an impeller 124 fixed to a shaft 126 which projects through the outer wall of housing 118 for purposes of having a driven sheave 128 fixed thereto to be driven by a driving sheave 130 mounted on the drive shaft of another source of power comprising an electric motor 131. An endless flexible belt 132 connects the sheaves. If desired, the sheaves and belts may be of a multiple nature as illustrated in FIG. 2 in particular.

When it is desired to blow pulverant material from chute 108 by the use of the blower 118, it is essential that the blower be provided with a certain amount of inlet air through the opening 118 in the housing of the blower. The present invention is admirably suited to provide a controlled and adjustable amount of such inlet air which will pass through the open top of trough 108, as shown in exemplary manner. Such discharge of material is accomplished, however, without ingress of ambient air to the interior of the silo. Such inlet air is illustrated in exemplaryimanner by the arrow 134 in FIG. 2 and the appropriate legend.

Particularly at the completion of a discharging operation, when the motor 46 has been stopped to render the auger 62 and dislodging members 74 and 76 idle, the blower motor 130 continues to operate 'and the closure 84 is moved to troughclosing position such as shown in broken lines in FIG. 4.

When the closure is in trough-closing position, the blower can only obtain air from the interior of the silo shell 10. As a result, a negative pressure is created within the silo shell, thereby minimizing the residual amount of oxygen in the stored material, particularly when the same is silage for agricultural use. Under such circumstances, the blower 118 is continued in operation for a desired amount of time, after which the closure 84 is quickly moved into engagement with the discharge opening 30 so as to close and seal the same against the inlet of air due to the gasket 136 provided around the rim of the inner surface of closure 84, as best shown in FIG. 4. As in regard to the embodiment illustrated in FIG. 10, the discharge conduit 122 shown in FIG. 3 extends upward and outward from blower 118, in exemplary manner, for the same reasons as described above with respect to the arrangement of FIG. 10.

FILLING AND VENTING MECHANISM Referring to FIGS. 1 and 11, it will be seen that the silo shell 10 is provided with a filling conduit or conductor 138 which is exterior of the shell 10 and preferably is vertical along one side thereof. Such conductor extends upwardly from a position spaced above the surrounding ground level. The upper portion of the conductor 138 also extends laterally across a portion of the top 12 of the silo shell and terminates in a curved discharge end 140 which preferably is tightly fitted within the filling opening 14 in the top 12. The curved portions of the conductor 138 also preferably have appreciable radii so as to minimize any possibility of clogging or sloppage of the material while being blown upwardly through conduc tor 138 and into the silo by any appropriate means such as a portable blower or otherwise which may be connected to the lower end of conductor 138. If desired, the upper transversely extending portion of conductor 138 and terminal end 140 may be enclosed within the top portion of top 12 immediately beneath the top and thereby insure greater airtightness. To facilitate connection thereof with a blower, the lower end of conductor 138 preferably has a slidable extension 142 movable axially therein and terminating in a flange to which a closure plate, not shown may be tightly attached so as to prevent the ingress of ambient atmospheric air into the interior of the silo shell 10 when the filling operation has been completed.

Cooperating with the filling conductor 138 is a venting conductor 144 which preferably is tubular and, like the conductor 138, preferably is formed from metal or other suitable material. The venting conductor 144 also extends upwardly exteriorly of the side of the silo shell 10 and the upper end thereof also is bent inwardly toward the axis of the silo and terminates in an inlet 146 which is tightly connected to the vent opening 16. The lower end of the venting conductor 144 is adjacent *he surrounding ground level and is provided with a suitable air-regulating means such as a damper 148. Details of an exemplary damper are shown in FIG. 18. The damper preferably is pivotally movable about an axis 150`relative to an internal flange 152.

The venting conductor 144 has a dualfunction; one is to permit the discharge of air or other gases fromv within the silo while it is being filled and the other is to serve as an indicator when the silo has been substantially filled. The latter is accomplished by some of the material being blown into the top of the silo shell, when it is nearly filled, passing through the inlet end 146 of the conductor 144 and dropping down through the open, lower end of the conductor, where an attendant readily can see the material and thus know that the silo is substantially filled without having to climb to the top thereof to determine the same. In view of this, the filling and indicating means described above permits the silo to be filled, under controlled conditions which may be observed by an operator on the ground rather than having to climb to the top of the silo.

When the silo has been substantially filed as indicated by material falling from the lower end of conductor 144, blowing of the material through the filling conductor 138 is stopped, the aforementioned closure plate is fastened to the flanged lower end of slidable extension 142, and the damper 148 in the lower end of venting conductor 144 is moved to closed position, whereby the upper portion of the silo is sealed against the ingress of ambient atmospheric air at the top of the silo. The closure 84 will maintain the bottom portion of the silo sealed against the ingress of ambient atmospheric airl Particularly when the silo is placed under a. negative pressure by the use of the blower 118, the oxygen content of the material stored within the silo shell 10 can be reduced to a level where it will not appreciably adversely affect the contents, especially where the same is in the nature of moist silage for agricultural purposes.

AUXILIARY BOTTOM DISCHARGE APPARATUS With respect to FIG. 1, it has been described hereinabove that when the contents of silo have been discharged as far as is possible by the use of the auger 62 and material-engaging means 74 and 76, there will be a compacted residue 82 of the material, the upper surface of which is substantially conical or hemispherical. Under present circumstances, removal of this final amount of the material generally is accomplished manually and requires that an operator climb into the interior of the silo through a manhole 154, shown in FIG. 11 diagrammatically. Normally, the manhole is closed tightly by a suitable cover, not shown. The manhole also preferably is adjacent the axis of the silo and, correspondingly, is adjacent the discharge opening 32 in the bottomthereof and also in the top of the discharge housing 26. In such region, the residual material is relatively thin and no difficulty is experiences in entering the interior of the silo. Digging the material out manually however is an undesirable job. The present invention obviates such manual operation by the use of the auxiliary unloading mechanism now to be described.

Referring to FIGS. 14-17, and particularly FIG. 14, it will be seen that appropriate portions of the silo shell 10 and bottom 22 are illustrated in relation to the auger 62, If desired, one of the bolts 64 which secures the auger to the shaft 38 may be removed, such as the lower bolt, and a similar bolt 64' of the same diameter, but longer in dimension, is substituted therefor in order that a clevis 156 may be pivotally supported by said bolt and correspondingly by the shaft 38. The clevis has axially aligned bearing openings therein which receive the bolt 64'. If desired, suitable bushings may be included in the pivoting arrangement as shown in exemplary manner in FIG. 16 on a larger scale than in FIG. 15. Rigidly connected to clevis 56 is an arm 158 which may be formed from suitable tubular material. The connection 160 may be effected by welding and the length of the combined clevis 156 and arm 158, between the bearing openings in the clevis and the outer end of said arm, is less than the radius of the interior of the silo shell 10.

Arranged at suitable spaced differences along the arm 158 are a plurality of straps or sleeves 162, formed from metal and having a pair of parallel ears on the lower side which receive therebetween the upper end of astrut 164. Said end of the strut may be secured to the ears on sleeve 162 by riveting, bolts, or weldments, or combinations thereof. Further, relative rotation between the sleeve 162 and'arm 158 is prevented by means of a transverse bolt 166 or other equivalent means, extending therethrough as shown in FIG. 17.

Also as shown in FIG. 17 in particular, as well asin FIG. 16, it will be seen that the upper and lower ends of each strut 164 is twisted about its longitudinal axisto dispose said ends substantially at approximately 45 to each other as seen from FIG. 16. The lower end of each strut 164 is provided with a suitable boss 166 to receive a pintle 168 upon which a disc 170 is rotatably supported. Such discs are all respectively disposed at a desired angle with respect to the axis of arm 158, as can be visualized from FIG. l5, so that when thearm is rotated in the direction of ihe arrow shown in FIG. 1S, said discs will dig o r plow the upper surface 80 of the compacted residual material 82 and gradually reduce the height thereof and move the material toward the discharge opening 30. As the material gradually is removed from the upper surface, the arm 158 will lower by gravity until, ultimately, the discs are riding upon the upper surface of bottom 22 of the silo shell 10. At this stage, substantially all of the residual material will have been removed and discharged through the opening 30. If desired, the arm 58 may be braced with respect to clevis 156 by means of exemplary braces 172, shown in FIG. 16, or the equivalent thereof. Further, in lieu of clevis bolt 64', a suitable friction clutch, not shown, may be used and thereby prevent damage to the mechanism if it is overloaded in operation.

MULTIPLE-UNIT ARRANGEMENTS Under circumstances where silos of abnormal diameter are desired or required, such as of the order of 30 or 40 feet, or greater, it is preferred to use a plurality of the unloading units of the type illustrated in FIGS. 1-6, each of the same being mounted adjacent an appropriate discharge opening formed in the bottom of such larger type of silo. lt also is contemplated that each of such units will include a discharge housing 26 and a desired embodiment of discharge and removal mechanism to be employed therewith. If desired under the circumstances, each of the discharge housings 26 may deliver the product to a common removal apparatus of either'of `the types described hereinabove respectively illustrated in FIGS. l and 10, and in FIGS. 2-6, or otherwise.

Referring to FIGS. 1 and 13, it will be seen that the paths 172 described by the outer end of the longest flexible material engaging members 74 should preferably overlap in order to function to the highest efficiency in any given unloading operation. Under such circumstances, it is essential that the flexible members not interfere with each other. Accordingly, to prevent this, and as illustrated somewhat diagrammatically in FIGS. 12 and 13, it will be seen that appropriate indexing means 174 are employed. Such means may comprise a sprocket chain extending around appropriate sprocket gears respectively fixed to the drive shaft 38 of each unit. Further under such circumstances, it is possible to use only a single power unit such as illustrated inthe lower portions of said FIGS. which units are connected toA one of the augers 62 and the shaft which drives the same. A motor of appropriate power is used to simultaneously drive all of the unloading units in each of the exemplary arrangements respectively shown in FIGS. 12 and 13 which, incidentally, are intended to be illustrative only and not restrictive.

We claim: a A

1. Bottom discharge means for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top covering the upper end thereof and a bottom extending horizontally across the lower portion of the shell and provided with a discharge opening in said bottom adjacent the center thereof, said discharge means comprising in combination a discharge housing adapted to be attached to said bottom and extend downwardly 'therefrom beneath said discharge opening therein to receive stored material therethrough from said silo shell, a downwardly and outwardly sloping discharge guide in said housing in substantially vertical alignment with said discharge opening and terminating at its lower end with a discharge port, a closure movably carried by said discharge housing and positionedvnormally to close said discharge port but movable away from said port to permit discharge of material therethrough, ashaft sufficiently long to extend vertically upwardly from said discharge housing into at least the lower portion of such siloshell, a spiral auger having a coarse pitch and substantial diameter carried by said shaft above the level ofsaid bottom of said silo, power means operable to rotate said shaft and auger at a predetermined speed and in a direction to cause said auger to forcibly feed material from said silo shell to and through said discharge openings, and a plurality of flexibly radially extendable dislodging members of a length less than the radius ofI said silo shell interconnected to said shaft within the lower portion of said silo shell and having weighted digging members on the outer ends thereof operable when rotation ofsad shaft is initiated to cause gradual movement of the outer Vends of said flexible dislodging members outwardly from said shaft and thereby efl fect dislodgement of impacted stored material in said silo shell and movement thereof by gravity into engagement with said auger for discharge through said discharge opening in said bottom.

2. The bottom discharge means according to claim l in which said closure for said discharge port of said housing is supported for pivotal movementoutwardly from its closed position to an open position to effect said discharge of material through said port.

3. The bottom discharge means according to claim 2 further including material dislodging means carried by said closure and operable during opening movement of said closure to initially dislodge accumulated material disposed in said discharge housing adjacent said discharge port thereof.

4. The bottom discharge means according to claim 1 in which said power means for said shaft isl supported adjacent the lower portion of said discharge housing and said shaft extends through said sloping discharge guide of said housing for connection to said power means outwardly from said discharge guide.

5. The bottom discharge means according to claim 1 in which said discharge housing in association with said silo bottom is provided with an entrance opening in the top thereof, said opening being of semicircular configuration and said discharge means further including a wiper arm interconnected at one end of said shaft and extending radially therefrom adjacent and above said semicircular entrance opening, said wiper arm being operable to wipe material from the top of said housing into said discharge opening.

6. Bottom discharge mechanism for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top and bottom andi a discharge opening in the bottom adjacent the center thereof, said discharge mechanism comprising in combination, a discharge housing adapted to be interconnected to said silo bottom beneath said discharge opening therein to receive stored material therethrough, discharge guide means in said housing terminating is in a discharge port, a closure for said discharge port mounted for movement between open and closed positions relative to said port, a blower having inlet and discharge lill means mounted in spaced relation to said closure, power means to drive said blower, and chute means extending between said discharge port and the inlet means of said blower to deliver material to said blower for delivery through the discharge means thereof, said closure being movable within said chute means and operable relative thereto and the inlet of said blower to control the amount of ambient air capable of passing into the inlet of said blower for the blowing of material by said blower away from said discharge means.

7. The bottom discharge mechanism according to claim 6 in which said chute means has an open top and said closure for said discharge port being positioned for movement relative to said open top of said chute means and said discharge port to establish desired operating conditions for said blower and under conditions which permit no ingress of ambient air to the interior of the silo during discharge of material.

8, The bottom discharge mechanism according to claim 6 in which said discharge guide means and chute means slope downwardly and outwardly relative to said discharge opening in said bottom of said silo, and said closure being pivotally supported adjacent the upper edge thereof for movement between a position in which it closes said discharge port and a second position in which it closes the top of said chute when desired and thereby preventing the ingress of ambient air to said fan when said top is closed thereby so as to cause a negative pressure within a silo shell such as after a filling operation has been completed.

9. The bottom discharge mechanism according to claim 6 in which the sides of said chute are substantially vertical and parallel to each other when in operative position and the top is open, the upper edges of said sides of said chute being provided with flanges inturned toward each other and said closure being pivotally supported substantially at the upper edge thereof adjacent said discharge port for movement between closing position relative to said discharge port and a position in which said closure engages said inturned flanges to close the top of said chute against the ingress of ambient air to said blower.

lb. The bottom discharge mechanism according to claim 9 further including positioning means interconnected to said closure and operable to secure the same respectively in said several closed positions and also in intermediate position therebetween. Y

l1. The bottom discharge mechanism according to claim 6 in which said blower is provided with tangential discharge means extending upwardly and outwardly therefrom.

l2. The bottom discharge mechanism according to claim 6 further including dislodging means connected to said closure an extending into said discharge guide means in said housing to dislodge the lowermost portion of compacted material in said guide means when said closure is moved toward open position to effect discharge of material from said guide means and discharge port thereof,

13. ln combination with a silo for storing pulverant material such as agricultural products and having a vertical cylindrical shell provided with a top and bottom at opposite ends and the bottom having a discharge opening therein; discharge means `for stored material-positioned below a said discharge opening in said bottom and operable to receive material from the bottom of said silo for discharge thereof as desired; and loading means for said silo comprising a tubular filling conductor adjacent the exterior of said silo shell land extending upwardly from the lower portion thereof to the top thereof and communicating with a substantially central inlet port in said top, the lower end of said filling conductor having means for connection of blowerlike filling mechanism thereto, combination vent and indicator means comprising another tubular conductor extending upwardly along the exterior of said silo shell from the lower portion thereof to the top of said silo and communicating with a vent opening in said top, and air flow-control means in said vent and indicator means operable to control the discharge of air from said silo while being filled and also seal the vent means against inflow of air at the completion of filling said silo, said vent conductor also being adapted to discharge a limited quantity of material downwardly therethrough when the same reaches said another opening in the top of the silo and thereby serve as an indicator when it is substantially full, whereby a silo may be both filled and emptied without requiring an operator to climb tothe top thereof.

14. The silo according to claim 13 inwhich said air flowcontrol means in said vent comprises adamper pivotally supported.

l5. The silo according to claim 13 further including means connectable to the inlet end of said filling conductor to seal the same against the ingress of ambient air at the completion of a filling operation. l

i6. The silo according to claim 13 in which said vent opening in the top of said silo is at a lower level then the filling opening therein.

17. Bottom discharge mechanism for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top and bottom and discharge opening in said bottom and a manhole in said bottom adjacent said opening, said discharge mechanism comprising a shaft, means to support said shaft for rotation about a vertical axis and adapted to extend up through a silo bottom, an auger having a coarse pitch and appreciable diameter supported by the upper portion of said shaft for rotation above the bottom of a silo shell, and power means connected to said shaft to rotate the same and the auger connected thereto, a plurality of flexible members interconnected to said shaft above the bottom of a silo and arranged to extend radially by centrifugal force to dislodge stored material when said shaft and auger are rotated, said flexible members being spaced vertically upon said shaft and the uppermost members being longer than the lower ones but all being of less length than the interior radius of a silo shell, whereby a residue of compacted stored material remains in the bottom of said shell having a generally conical upper contour after a silo has otherwise been emptied by said discharge mechanism, in combination with auxiliary discharge means interconnectable detachably to said shaft and including an arm having connecting means on one end adapted to be interconnected to said shaft and extend radially across the upper surface of said residue material, and removing means supported by said arm and operable to dig into said residue material and cause it to move to said discharge opening in the bottom of a silo shell.

18. The bottom discharge mechanism according to claim 17 in which said connecting means for said arm comprises means pivotally interconnecting said one end of said arm to said shaft.

19. The bottom discharge mechanism according to claim 18 in which said means pivotally interconnecting one end of said arm to said shaft comprises a clevis partially surrounding said shaft and auger and including a pin extending radially through said shaft to support the arms of said clevis, whereby said arm is driven rotatably about the axis of said shaft when said shaft is rotated by said power means.

20. The bottom discharge mechanism according to claim 18 in which said removing means supported by said arm comprise a plurality of angularly arranged digging members supported at spaced locations along said arm, said members extending in a direction to engage and move compacted material radially inward toward the axis of the shaft for discharge through the discharge opening in the bottom of a silo.

21. The bottom discharge mechanism according to claim 20 in which said angularly arranged digging members comprise discs rotatably supported by members connected to said arm.

22. Bottom discharge mechanism for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top and bottom and said bottom having a plurality of discharge openings therein arranged substantially even radial distances from the central axis of the shell and spaced even circumferential distances from each other, said discharge mechanism comprising a plurality of similar shafts extending upward through the bottom of a silo adjacent said sof sprocket chain extending between and around said sprocket gears to drive the same simultaneously', said flexible dislodging members interconnected to said shafts being indexed relative to each other by said sprocket gears and chain, whereby the flexible members pass each other without interference with each other during rotation of said shafts. 

1. Bottom discharge means for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top covering the upper end thereof and a bottom extending horizontally across the lower portion of tHe shell and provided with a discharge opening in said bottom adjacent the center thereof, said discharge means comprising in combination a discharge housing adapted to be attached to said bottom and extend downwardly therefrom beneath said discharge opening therein to receive stored material therethrough from said silo shell, a downwardly and outwardly sloping discharge guide in said housing in substantially vertical alignment with said discharge opening and terminating at its lower end with a discharge port, a closure movably carried by said discharge housing and positioned normally to close said discharge port but movable away from said port to permit discharge of material therethrough, a shaft sufficiently long to extend vertically upwardly from said discharge housing into at least the lower portion of such silo shell, a spiral auger having a coarse pitch and substantial diameter carried by said shaft above the level of said bottom of said silo, power means operable to rotate said shaft and auger at a predetermined speed and in a direction to cause said auger to forcibly feed material from said silo shell to and through said discharge openings, and a plurality of flexibly radially extendable dislodging members of a length less than the radius of said silo shell interconnected to said shaft within the lower portion of said silo shell and having weighted digging members on the outer ends thereof operable when rotation of said shaft is initiated to cause gradual movement of the outer ends of said flexible dislodging members outwardly from said shaft and thereby effect dislodgement of impacted stored material in said silo shell and movement thereof by gravity into engagement with said auger for discharge through said discharge opening in said bottom.
 2. The bottom discharge means according to claim 1 in which said closure for said discharge port of said housing is supported for pivotal movement outwardly from its closed position to an open position to effect said discharge of material through said port.
 3. The bottom discharge means according to claim 2 further including material dislodging means carried by said closure and operable during opening movement of said closure to initially dislodge accumulated material disposed in said discharge housing adjacent said discharge port thereof.
 4. The bottom discharge means according to claim 1 in which said power means for said shaft is supported adjacent the lower portion of said discharge housing and said shaft extends through said sloping discharge guide of said housing for connection to said power means outwardly from said discharge guide.
 5. The bottom discharge means according to claim 1 in which said discharge housing in association with said silo bottom is provided with an entrance opening in the top thereof, said opening being of semicircular configuration and said discharge means further including a wiper arm interconnected at one end of said shaft and extending radially therefrom adjacent and above said semicircular entrance opening, said wiper arm being operable to wipe material from the top of said housing into said discharge opening.
 6. Bottom discharge mechanism for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top and bottom and a discharge opening in the bottom adjacent the center thereof, said discharge mechanism comprising in combination, a discharge housing adapted to be interconnected to said silo bottom beneath said discharge opening therein to receive stored material therethrough, discharge guide means in said housing terminating is in a discharge port, a closure for said discharge port mounted for movement between open and closed positions relative to said port, a blower having inlet and discharge means mounted in spaced relation to said closure, power means to drive said blower, and chute means extending between said discharge port and the inlet means of said blower to deliver material to said blower for delivery through the discharge means thereof, said closure being movable within said chute means and operable relative thereto and the inlet of said blower to control the amount of ambient air capable of passing into the inlet of said blower for the blowing of material by said blower away from said discharge means.
 7. The bottom discharge mechanism according to claim 6 in which said chute means has an open top and said closure for said discharge port being positioned for movement relative to said open top of said chute means and said discharge port to establish desired operating conditions for said blower and under conditions which permit no ingress of ambient air to the interior of the silo during discharge of material.
 8. The bottom discharge mechanism according to claim 6 in which said discharge guide means and chute means slope downwardly and outwardly relative to said discharge opening in said bottom of said silo, and said closure being pivotally supported adjacent the upper edge thereof for movement between a position in which it closes said discharge port and a second position in which it closes the top of said chute when desired and thereby preventing the ingress of ambient air to said fan when said top is closed thereby so as to cause a negative pressure within a silo shell such as after a filling operation has been completed.
 9. The bottom discharge mechanism according to claim 6 in which the sides of said chute are substantially vertical and parallel to each other when in operative position and the top is open, the upper edges of said sides of said chute being provided with flanges inturned toward each other and said closure being pivotally supported substantially at the upper edge thereof adjacent said discharge port for movement between closing position relative to said discharge port and a position in which said closure engages said inturned flanges to close the top of said chute against the ingress of ambient air to said blower.
 10. The bottom discharge mechanism according to claim 9 further including positioning means interconnected to said closure and operable to secure the same respectively in said several closed positions and also in intermediate position therebetween.
 11. The bottom discharge mechanism according to claim 6 in which said blower is provided with tangential discharge means extending upwardly and outwardly therefrom.
 12. The bottom discharge mechanism according to claim 6 further including dislodging means connected to said closure an extending into said discharge guide means in said housing to dislodge the lowermost portion of compacted material in said guide means when said closure is moved toward open position to effect discharge of material from said guide means and discharge port thereof.
 13. In combination with a silo for storing pulverant material such as agricultural products and having a vertical cylindrical shell provided with a top and bottom at opposite ends and the bottom having a discharge opening therein; discharge means for stored material positioned below a said discharge opening in said bottom and operable to receive material from the bottom of said silo for discharge thereof as desired; and loading means for said silo comprising a tubular filling conductor adjacent the exterior of said silo shell and extending upwardly from the lower portion thereof to the top thereof and communicating with a substantially central inlet port in said top, the lower end of said filling conductor having means for connection of blowerlike filling mechanism thereto, combination vent and indicator means comprising another tubular conductor extending upwardly along the exterior of said silo shell from the lower portion thereof to the top of said silo and communicating with a vent opening in said top, and air flow-control means in said vent and indicator means operable to control the discharge of air from said silo while being filled and also seal the vent means against inflow of air at the completion of filling said silo, said vent conductor also being adapted to dischArge a limited quantity of material downwardly therethrough when the same reaches said another opening in the top of the silo and thereby serve as an indicator when it is substantially full, whereby a silo may be both filled and emptied without requiring an operator to climb to the top thereof.
 14. The silo according to claim 13 in which said air flow-control means in said vent comprises a damper pivotally supported.
 15. The silo according to claim 13 further including means connectable to the inlet end of said filling conductor to seal the same against the ingress of ambient air at the completion of a filling operation.
 16. The silo according to claim 13 in which said vent opening in the top of said silo is at a lower level then the filling opening therein.
 17. Bottom discharge mechanism for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top and bottom and discharge opening in said bottom and a manhole in said bottom adjacent said opening, said discharge mechanism comprising a shaft, means to support said shaft for rotation about a vertical axis and adapted to extend up through a silo bottom, an auger having a coarse pitch and appreciable diameter supported by the upper portion of said shaft for rotation above the bottom of a silo shell, and power means connected to said shaft to rotate the same and the auger connected thereto, a plurality of flexible members interconnected to said shaft above the bottom of a silo and arranged to extend radially by centrifugal force to dislodge stored material when said shaft and auger are rotated, said flexible members being spaced vertically upon said shaft and the uppermost members being longer than the lower ones but all being of less length than the interior radius of a silo shell, whereby a residue of compacted stored material remains in the bottom of said shell having a generally conical upper contour after a silo has otherwise been emptied by said discharge mechanism, in combination with auxiliary discharge means interconnectable detachably to said shaft and including an arm having connecting means on one end adapted to be interconnected to said shaft and extend radially across the upper surface of said residue material, and removing means supported by said arm and operable to dig into said residue material and cause it to move to said discharge opening in the bottom of a silo shell.
 18. The bottom discharge mechanism according to claim 17 in which said connecting means for said arm comprises means pivotally interconnecting said one end of said arm to said shaft.
 19. The bottom discharge mechanism according to claim 18 in which said means pivotally interconnecting one end of said arm to said shaft comprises a clevis partially surrounding said shaft and auger and including a pin extending radially through said shaft to support the arms of said clevis, whereby said arm is driven rotatably about the axis of said shaft when said shaft is rotated by said power means.
 20. The bottom discharge mechanism according to claim 18 in which said removing means supported by said arm comprise a plurality of angularly arranged digging members supported at spaced locations along said arm, said members extending in a direction to engage and move compacted material radially inward toward the axis of the shaft for discharge through the discharge opening in the bottom of a silo.
 21. The bottom discharge mechanism according to claim 20 in which said angularly arranged digging members comprise discs rotatably supported by members connected to said arm.
 22. Bottom discharge mechanism for use with a silo for storing pulverant material and including an upstanding cylindrical silo shell having a top and bottom and said bottom having a plurality of discharge openings therein arranged substantially even radial distances from the central axis of the shell and spaced even circumferential distances from each other, said discharge mechanism comprising a plurality of similar shafts extending upward through the bottom of a silo adjacent said discharge openings, an auger of coarse pitch and appreciable diameter affixed to each shaft and extending upward above the bottom of a silo, a plurality of flexible dislodging members interconnected to said shaft and having lengths no greater than half the radius of a silo shell, power means connnected to at least one of said shafts to rotate the same unidirectionally about its axis, sprocket gears connected to all of said shafts, a sprocket chain extending between and around said sprocket gears to drive the same simultaneously, said flexible dislodging members interconnected to said shafts being indexed relative to each other by said sprocket gears and chain, whereby the flexible members pass each other without interference with each other during rotation of said shafts. 